Air brake for drawworks



A. A. ASHTON AIR BRAKE FOR DRAWWORKS Nov. 10, 1953 3 Sheets-Sheet 1 Filed April '7, 1950 irlk INVENTOR. QZBEET x9. fiSf/TON A. A. ASHTON Nov. 10, 1953 AIR BRAKE FOR DRAWWORKS 3 Sheets-Sheet 2 Filed April 7, 1950 INVENTOR. HLBEET 19. HSHTON arrow 5;

Nov. 10, 1953 Filed April 7 1950 A. A. ASHTON AIR BRAKE FOR DRAWWORKS 3 Sheets-Sheet 3 &4.

P26880106 PEES'SUEE 6569,66 BEAM E 829 66 OFF ON ON l/fiZl/E I/flLl/E VHLVE INVENTOR.

OFF meg/er R. may/mu HTCQENEV Patented Nov. 10, 1953 AIR. BRAKETOR DRAWWORKS Albert A; Ashton; Houston, Tex-q, assig-nor to.

Emsco :Manufaeturing Company,,Los. Angeles, Galit., a-corporation of California,

Application April -7,' 1950; Serial-N6. 154540 4 -'Claims.-- (01. 188 -151).

The present inventionl-relatesgenerally to heavy duty band brakes of the type 'zutilizedzin the oil drilling: industry for: drawworks; 'l and is more particularly concerned with improved ac' t'uating'meansr and control therefor.

It is anobject of the herein describedinven+ tion to provide an improved braking mechanismf having'a brake whichis: movedtoward' and :away frornaazibrake. drum'by-a fluid cylinder actuator utilizing a fluid. such 'asair underfpressure, and which.-may1 also be actuated. mechanically-"by means? of .a a hand 1 lever.

Akfurtheraobject of the invention is to provide a: simplified equalizing mechanism' in a-drawworks brake:which permitsxactuation of :the brake byreither a fluid actuator or." mechanically by means of ia hand lever'," eventhough one of'the brakestfails's to: operate;

Still anotherlobijecti of :the invention isto provide. in azbraking -mechanism fluid actuator means andicontrol', wherein a relatively. low' fluid pressure: is: normally utilized to operate; the brake elementscto. braking 'position, and-a higher. fluid pressure. 'isi-utilized;:forziractuating the brake elemel'lllS-td none-braking. position, and for au'gm'entingthe braking .effect in; case of emergency; and at -sucli times; as the normal low fluid. pressure iszinsuificient'; to 'give' the. required braking effect.

Further ob'j'ectsrofzth'e invention will .be'brought out the. following. part of' the specification, whereindetailed description is. for thevpurpose of fully disclosingthe invention without placing limitationsson its scope.-

Referring to the drawings, WhiCh'JELI'BI'fOI .illuse. trative purposes only:

Fig; 1tisia sidezelevational view .of a Fbrake embodyingthe- 'features of; the; present invention;

Fig; 2 -i is sazrear: elevational. view taken from thepositio indicated byfthez arrow 2 .of Fig. 1;.

li'i'g. 31is; a: fragmentary-plan View" of: the :brake actuating smechanism; partly. in section',z.the-..:sec= ti'ombei-n'gs taken substantially. on: line 3'3 of Fig-r11; and

Fig; ,4 is: a -view diagrammatically; showing-the fluid supply'and control for the fluid actuator of thezbrake:

Referring snow to :the drawings; Figs: 1 and 2 show the brakeof the present invention aszcomprising .a: setaotbrake bands l-I0 disposedin spaced. relation so as to engage the. drums l l--l l respectively; at the ends of a cable spool. l2, shown inphantomlin'esv Each brake bandll n comprises a split ring I3'ofspring steel or other suitable material to which brake blocks. M of suitable friction bi'akeJining material are secured. for engagement'with the associated drums Whenthe brake bands are constricted or tightened during the' braking operation.

One end of each" brake band assembly I 0 is anchored so as to form a dead end by means. of an" en'dbracket15*which is pivotally connected by apivot pin l 6 *withpneend' of an adiusting rod? ll -havin'grpits othen'end threaded. The

threadectendrofj'theadjusting rod I1 is fitted with-a tubularcsleevew i -which is mounted-in diametricallyv positioned openings in a pipe.

structural/member l9==rigidly supported to form ansanchori Onoppositesides-of the pipel9-at the ends-10f; the: sleeve [8; the'ad-justing rod is. provided withwadapter fittings" 2i]20 againstwhich clam-ping. nuts 21 and 22 may be tightened to secure-"the'adjusting rod ll in-adjusted-po-- sition endwise -inthesstructural member l9.-

Thetother- .end or live end of the brake'bandassembly; is provided. with an end bracket 23 Which-is; pivotally connected by apivot pin 24 with .anactuating link-25; the links 2 5--2 5 of the two brake-bandassembliesbeing connected at their opposite: .ends by pivot pins .2 6-2 6'} respectively-to-the-oppositeends-of-an equalizer bar 2-1 by: means of {which the: brake bands. are simultaneouslyoperableyand between which the opcratingforces v ar-e J equalized.

The. brake band. assemblies ll] are normally biased 71 toward non-braking or released position by means offa co-iled spring ,2 8,. in each case, having one end connected totheendbracket'Zi-l and its :otherto aneye bolt 29 'anchored'by securing nuts :39. 30-in.aframe member 3 by asimple adjustment o f theeye bolt 12 9' in the frame member..3l, the-:tension-of the spring. 28" may be ad; justedto varyits-openingor' releasing. action of thabrakebandr Moreover, the brake bands may. be individuallyadjusted to. accommodate any variations which may. appearin one brake band andnot in. the. other.

In order thatthe operatinglforces Will be symmetricallyapplied'to'the ends of "the'brake band assembly, it will be observedthat each actuating link'"25"is provide'dwithan elongate slot 32"00 which the associatedadjusting rod l! is" carried; thelink "25" and adjusting rod H' 'thus being'disposed in crossedrelation at the rear side of the brake'drums:

Supported below and adjacentto the equalizer bar-21 from an a'djacent part of the frame struc ture --b'y-m'eans -of*"-b'o1ts" 33 1s a bearing housing 34- W-ithin WhiCh' shaft 1 35 is rotatable. The ends. offithe shaft? .35n'project .-from". either end. of the-housing; and are .zrespectively provided 9 with anglewlevers :36'and 31 which arekeyed or other--. Wisefi-Xably securecl z-to the: shaft SE -for rotation therewith The anglerlever 36 is Uesh-aped-having spaced apart.1egs; 38.-.and.39 between which one endot an..equalizerconnection clevis 451 isconnectedby a pivot pin 4'1, the opposite end 10f. this clevis beingpivotallyl con'nectediby a pivot pin 42. to the. adjacent margin of the equalizer bar. In angular. relation" to the"pivot"pin 4!, and. disposedat a greater distance from the center of rotation"ofitlie" shaft 35;. is a second pivot pin 43 "which pivotally-connects one end of a piston rod"44"of"a' fiiiid"acti1ator45 to the angle lever 36, whereby reciprocable movements of the piston rod act to angularly transmit its movements through the angle lever 36 to the clevis 40 so as to actuate the brake bands to the equalizer bar 21 and actuating links 2525.

The fluid actuator comprises a piston 46, as schematically represented in Fig. 4, which is reciprocably mounted within an associated cylinder 41, one end of this cylinder having a fluid connection 48 at one end and a fluid connection 49 at its other end. As shown in Fig. 3, the cylinder 4'! is positioned between spaced bracket plates 56-56 and is rockingly supported between its ends on trunnions l-5I. The angle lever 31 at the other end of the shaft 35, instead of being U-shaped is of single plate construction and is connected by an inner pivot pin 52 to the straddling bifurcated end 53 of a safety link 54 which is connected by a pivot pin 55 to the equalizer bar 21 at a point spaced from the pivot pin 42 at the center of the equalizer bar 21. As shown, the pivot pin 55 is positioned between pivot pins 42 and 26, being more closely disposed to the pivot pin 26. The pivot pin 55 extends through a slightly elongated opening 56 in the equalizer bar so as to provide a loose connection which will permit a limited angular movement of the equalizer bar 21 about the pivot pin 42. Thus, should restraint be removed from one end of the equalizer bar 21, it may swing on the pivot pin 42 until the pivot pin engages one end of the opening 56. Thereafter, the angle of the equalizer bar cannot change and it will then be bodily moved in response to the swinging of the angle levers 36 and 31 in response to the brake actuating means. With this arrangement, failure of either one of the brakes will not prevent the remaining brake from operating in response to the brake actuating mechanism.

In addition to the fluid actuator for operating the brakes, the brakes are also arranged to be independently operated mechanically. As primarily shown in Figs. 1 and 2, a bearing housing 51 is supported by bolts 51a from an adjacent portion of the frame structure at the front side of the drawworks, this bearing housing serving to rotatably support a shaft 58 therein. One end of this shaft is connected with a lever arm 59 which is pivotally connected at its outer end by means of a pivot pin 60 to one end of the connecting rod 6?, the other end of this connecting rod being pivotally connected to an outwardly disposed pivot pin 62 carried by the angle lever 31.

The other end of the shaft 58 is extended beyond the bearing housing 51 and is keyed or otherwise secured to a segmental lever 63, a spacer sleeve 64 being interposed between the segmental lever 63 and the adjacent end of the bearing housing 51. The periphery of the lever 63 at its outer marginal edge is provided with an arcuate shoulder 65, and at one end of this shoulder with an abutment 66 which extends be.- yond the outer edge or face of the shoulder 65 in the line of movement of a hand lever 61 connected at its inner end to a sleeve 68 which is rotatable on the shaft 58 and retained thereon by an end washer 69 and cap screw 16. Thus, the lever 61 is freely swingable on the shaft, but when swung in a clockwise direction until it strikes the abutment 66 the lever will act to rotate the segmental lever 63 and manually actuate the brake bands toward braking position. Moreover, with the arrangement described, the seg- 4 mental lever 63 will follow the operation of the brake bands by the fluid actuator.

Should occasion arise where the fluid actuator is unavailable to operate the brake, and it is desired to operate the brake manually from the hand lever 61, provision is made for temporarily connecting the hand lever 61 with the segmental lever 63. For such purpose, the inner end of the hand lever 61 is provided with a threaded opening 11 which registers with a threaded opening in the arcuate cylinder 65 when the lever is against the abutment 66. By inserting a cap screw in these registered openings, the lever 61 may be secured to the segmental lever 65 for operating it in both clockwise and counter-clockwise directions.

When it is desired to maintain the brake in braking position for an extended period of time, the hand lever 61 may be locked in brake-on position by means of a handle lock which will now be described.

In concentric relation to the segmental lever 63, an arcuate plate 12 is supported at its ends as by bolts 13 from an adjacent part of the plane structure, this plate containing an arcuate slot 14. The plate 12 extends alongside the inner end portion of the handle lever 61 and is parallel to the plane of movement of this lever. A cap screw 15 is supported by the lever and extends inwardly over the outer edge and in spaced relation thereto of the arcuate plate 12, the threaded end of the cap screw 15 having a nut 16 threaded thereon Which serves as an abutment for a plate 11 slidably supported thereon. An expansion coiled spring 18 surrounding the shank of the cap screw has one end bearing against the adjacent surface of the hand lever 61 and its other end against the plate 11, this spring acting to normally bias the plate away from the hand lever against the abutment nut 16. The other end of the plate 11 has threadedly secured thereto a stud 19 which projects through the slot 14 and an aperture in the hand lever, the outer ends of this stud being provided with adjustable jamb nuts 80. Slidable on the stud 19 on the opposite side of the hand lever 61 from that on which the plate 11 is positioned, is a block 8| as shown in Fig. 1, which has oppositely extending trunnions 82 upon which a handle 83 is swingably supported. The pivoted end of this handle 83 is bifurcated and provided with spaced cam surfaces 8484 which lie on opposite sides of the studs 19 and are adapted to engage against a washer 85 interposed between the cam surfaces and the adjacent surface of the handle brake 61. With the blocking mechanism in the positions shown in Fig. 2, with the handle 83 depending, the hand lever 61 may be freely swung along the arcuate plate 12 within the limits of slot 14. To block the hand lever 61 against movement, the handle 83 is swung in a counterclockwise direction, as viewed in Fig. 2, to a raised position which causes the cam surfaces 84 to act in such a manner that the washer 85 and plate 11 are clampingly moved together to bind the hand lever 61 and arcuate plate 12 against relative movement and thus block the hand lever in position.

The handle 83, and associated elements may be used for locking the hand lever '61 in a substantially vertical position of non-use, when desired, in which position the handle is retained out of engagement with the abutment 66 of the segmental lever 63.

From the foregoing description, it is apparent that the brake may be independently actuated by either the fluid actuator 45, or by means of the hand lever 61 or a combination of both.

Control for the fluid actuator is schematically illustrated in Fig. 4, and comprises a primary air supply tank 99 adapted to contain air at a pressure of substantially 125 lbs. per sq. in., which is supplied from any suitable source through a supply connection Bl. An outlet connection 88 connects the tank 39 through a pressure regulator 89 and check valve 90 with an auxiliary air tank 9| containing air at substantially 75 lbs. per sq. in., pressure.

A double check valve 92 is connected with one of its inlet connections connected through a connection 93 with the auxiliary air tank 9|, and its other inlet connection connected through a connection 99, 94a and 88 with the primary tank 86. The branch connection of the double check valve is connected through a connection 95 with fluid connection 48 of cylinder 41.

The connection 94a leads to a regulating and emergency three-position valve 99 which is adapted to connect the primary tank pressure with connection 94 or a connection 9'! connecting with fluid connection 49 of the cylinder 41. Lubricators 98-98 are respectively positioned in the connection lines 99 and 91 for lubricating the interior of the fluid actuator.

Operation of the control for the fluid actuator will now be explained. With the control handle of valve 96 in mid position, as shown in Fig. 4, the valve being off, air at 75 lbs. pressure will be supplied from the tank 9| through the double check valve by connections 93 and 95 to the fluid connection 48 of the cylinder. Whereupon the piston 99 will be moved to the right in a direction which will apply the brakes.

In order to release the brakes, the valve handle is moved to the left to "valve-on position. This connects the 125 lb. air pressure from tank 86 through connection 94a with connection 9! to fluid connection 49. The air pressure of 125 lbs. on the opposite side of the piston 46 acts against the pressure of 75 lbs. so that the predominating force acting on the piston is such as to move it in a direction toward the left, which is such as to actuate the brake to release for non-braking position.

For emergency operation, when the normal 75 lb. pressure is insufficient to produce the required braking. or when it is desired to augment the braking efiect produced by the 75 lb. pressure, the valve control handle is moved to the right of its mid-position. In this position, the 125 lb. fluid pressure in the tank 8'6 is connected through connection 99a, connection 94, double check valve 92, connection 95 and thence to the fluid connection 98. The higher pressure in the double check valve causes it to cut off the 75 lb. fluid pressure supply from tank 91 so that instead of 75 lb. pressure acting to move the piston in brakeon direction, there is now a pressure of 125 lb. pressure acting to give increased braking eflect.

I claim:

1. A brake mechanism for a brake drum, comprising: a brake band operatively associated with said brake drum; a double acting fluid actuator connected to said brake band, operable in brake applying and brake releasing directions; a low pressure fluid source connected to operate said actuator in a brake applying direction; a high pressure fluid source; and control means for selectively connecting said high pressure source to said actuator so as to operate the actuator in said brake applying direction and thereby effect a forceful application of said brake band, or so as to oppose the action of said low pressure fluid and operate the actuator in a brake releasing direction.

2. In a mechanism for applying and releasing a brake: a first fluid pressure operable means connected to said brake and being adapted to exert a force to apply the brake and maintain the same in applied condition; means operable to deliver a brake applying fluid pressure to said first fluid pressure operable means; a second fluid pressure operable means connected to said brake in opposition to said first means; means including a control valve operable to selectively apply fluid pressure to said second fluid pressure operable means of sufficient magnitude to overcome the brake applying action of fluid pressure in said first fluid pressure operable means and effect release of said brake, and to release fluid pressure from said second fluid pressure operable means so that fluid acting in said first means will again apply the brake; and means operable to apply to said first fluid pressure operable means a fluid pressure greater than said brake applying fluid pressure.

3. In a mechanism for applying and releasing a brake: a first fluid pressure operable means connected to said brake and being adapted to exert a force to apply the brake and maintain the same in applied condition; means applying fluid pressure to said first fluid pressure operable means; a second fluid pressure operable means connected to said brake in oposition to said first means; and means including a control valve operable to selectively and alternately apply fluid pressure to said second fluid pressure operable means of sufficient magnitude to overcome the brake applying action of fluid pressure in said first fluid pressure operable means and effect release of said brake, and to apply a fluid pressure to said first fluid pressure operable means to increase the force with which it applies the brake.

4. A drawworks brake mechanism, comprising: a brake having a movable operating member; a double acting fluid pressure operated actuator connected to said operating member of said brake, said actuator having a brake applying pressure fluid inlet and a brake releasing pressure fluid inlet; a main high pressure fluid source; an auxiliary low pressure fluid source; a double check valve having one of its inlets connected to said low pressure source and its outlet connected with said applying pressure fluid inlet of said actuator; and means including a control valve adapted to selectively connect said high pressure source to the other inlet of said check valve and to said brake releasing pressure fluid inlet of Said actuamr- ALBERT A. ASHTON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 705,592 MacLaughlin July 29, 1902 1,311,030 Wood et al July 22, 1919 1,552,584 Sumner Sept. 8, 1925 1,833,167 Luzzi Nov. 24, 1931 1,987,435 Engel Jan. 8, 1935 2,371,856 Tremolada Mar. 20, 1945 2,371,857 Stevenson Mar. 20, 1945 2,422,370 Schnell June 17, 1947 2,464,469 Tremolada Mar. 15, 1949 FOREIGN PATENTS Number Country Date 459,433 Great Britain Jan. 4, 1937 

